Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define FOR(I,X,Y) for(int I=X;I<Y;I++)
#define REP(I,X,Y) for(int I=Y-1;I>=X;I--)
#define INF 1000000007
using namespace std;

int main(){
  int H,W,sharp=0;
  int dx[] = {0,0,1,-1};
  int dy[] = {1,-1,0,0};
  cin >> H >> W;
  char s[H+2][W+2];
  int bfs[H+2][W+2];
  FOR(i,0,H+2)FOR(j,0,W+2){
    s[i][j] = '#';
    bfs[i][j] = -1;
  }
  FOR(i,1,H+1)FOR(j,1,W+1){
    cin >> s[i][j];
    if(s[i][j] == '#')sharp++;
  }
  queue<pair<int,int>> que;
  que.push(make_pair(1,1));
  bfs[1][1] = 0;
  while(que.size()){
    FOR(i,0,4){
      int x = que.front().first + dx[i];
      int y = que.front().second + dy[i];
      if(s[x][y] == '.' && bfs[x][y] == -1){
        que.push(make_pair(x,y));
        bfs[x][y] = 1+bfs[x-dx[i]][y-dy[i]];
      }
    }
    que.pop();
  }
  if(bfs[H][W] == -1)cout << -1 << endl;
  else cout << H*W - sharp - bfs[H][W] - 1 << endl;
}